The present invention relates to a fan assembly for cooling an electronic device comprising a plurality of heat generating electrical components mounted in an enclosure, such as a server computer. In particular, the invention relates to a fan assembly comprising a row of fans which are oriented with their axis of rotation at an angle, such as ninety degrees, to the sidewalls of the enclosure. This will enable the fan assembly to deliver a required airflow through the enclosure with fewer fans. The number of fans can be chosen to achieve operation at peak efficiency without concern for the uniformity of the flow across the enclosure, as would be the case if the fans were mounted parallel to the sidewalls.
Prior art server computers typically include a number of heat generating electrical components mounted in an enclosure. Such computers commonly employ air to cool the components. Thus, prior art server computers usually include a number of internal fans for generating an airflow over the components. The airflow cools the components through the process of convection by absorbing the heat generated by the components and then dissipating the heat outside the enclosure.
An example of a prior art server computer is shown in FIG. 1. This server computer, generally 10, includes a number of electrical components which in this example are housed in a 1 u rack enclosure 12. The rack enclosure 12 comprises a front wall 14, a rear wall 16 and two parallel sidewalls 18. The front and rear walls each comprise a plurality of holes or apertures 20 through which air can pass. Several of the electrical components generate heat during operation of the server computer 10, such as a number of disk drives 22 which are located in a drive bay 24, a plurality of memory modules 26, two processors 28 (each of which is positioned under a corresponding heat sink 30), and one or more power supplies 32. In order to dissipate the heat generated by these components, the server computer 10 also includes a number of fans 34, in this case six, which are oriented with their axes parallel to the sidewalls 18. During operation of the server computer 10, the fans 34 draw air into the enclosure 12 through the apertures in the front wall 14 and force the air over the heat generating components and through the apertures in the rear wall 16. As the air flows over the components, the heat generated by the components is absorbed by the air to thereby cool the components.
In order to reduce the power consumed by the server computer, it is desirable to tailor the airflow distribution over the components so that each component will receive the airflow required to cool the component sufficiently. The current state of the art requires that a number of fans be distributed across the enclosure to provide a uniform airflow over all of the components, as well as to provide redundancy in the event one of the fans should stop operating. With the fans oriented parallel to the side ails as shown in FIG. 1, this often results in the use of a large number of fans operating at less than peak efficiency in order to generate the required airflows over each of the components.